LTM4705 PGOOD Function

[mayang]

Hi. I just wander on what supply I should pulled up to the resistor?

Here is the situation. In the LTM4705 IC from ADI, page 13 of its datasheet (

https://www.analog.com/media/en/technical-documentation/data-sheets/ltm4705.pdf

). it says that ". A resistor can be pulled up to a particular supply voltage for monitoring." This is a Dual Output IC and the input voltage is 12V and it will regulate to 5 and 3.3 volts.
My question is what supply should pulled up the resistor? it is the 12V input or the 5V and 3.3V???
Because if I where to ask, I think I should pulled up the resistor to 5v and 3.3V since the purpose of PGOOD is to monitor the valid out voltage.

Am I right or maybe wrong?? hahahah

Thanks in advance.

 

[FvM]

Depends on the input level of the circuit monitoring PGOOD state. If there's no circuit, PGOOD can be unconnected without pull-up.

 

[mayang]

Depends on the input level of the circuit monitoring PGOOD state. If there's no circuit, PGOOD can be unconnected without pull-up.

Hi FvM, I know that I can leave the PGOOD unconnected but since I am going to use in my circuit I think it is important, other than the connection of PGOOD in the power it is also connected to the Power Status Leds circuitry.

 

[KlausST]

Hi

My question is what supply should pulled up the resistor? it is the 12V input or the 5V and 3.3V???

Again I take the risk to get called "rude" when referring to the datasheet.

12V? Datasheet says "Absolute maximum voltage for PGOOD is 6.0V". So 12V is no option.

Figure 1 in the datasheet shows them to be connected to INTVCC via 10k. This is a valid option.

**
But indeed it enables you to adjust on the device where you want to connect the PGOOD signal to.
If it´s a 3.3V powered device, use 3.3V
If it´s a 5V powered device, use 5V

Klaus

 

[mayang]

Here is the schematic to make it clear.

 

[mayang]

Again I take the risk to get called "rude" when referring to the datasheet.

12V? Datasheet says "Absolute maximum voltage for PGOOD is 6.0V". So 12V is no option.

Figure 1 in the datasheet shows them to be connected to INTVCC via 10k. This is a valid option.

**
But indeed it enables you to adjust on the device where you want to connect the PGOOD signal to.
If it´s a 3.3V powered device, use 3.3V
If it´s a 5V powered device, use 5V

Klaus

okay I got it hahah thanks a lot sir, even I'm a bit rude sometimes.

 

[FvM]

Here is the schematic to make it clear.

Please try to post readable images.

"Power Status Leds circuitry" - where? how? No LEDs shown. Please show your intended circuit.

Most simple circuit would be a LED with 5 mA pull-up, shorted by PGOOD pin(s).

 

[mayang]

Hi

Again I take the risk to get called "rude" when referring to the datasheet.

12V? Datasheet says "Absolute maximum voltage for PGOOD is 6.0V". So 12V is no option.

Figure 1 in the datasheet shows them to be connected to INTVCC via 10k. This is a valid option.

**
But indeed it enables you to adjust on the device where you want to connect the PGOOD signal to.
If it´s a 3.3V powered device, use 3.3V
If it´s a 5V powered device, use 5V

Klaus

Hi sir, may I know what is the INTVcc is? I confuse about this pin.

 

[FvM]

Hi sir, may I know what is the INTVcc is? I confuse about this pin.

Datasheet? "Internal 3.3V Regulator Output" Because it's powered by an internal linear reulator, you don't want to draw much current from this pin.